Patent EP-4184918-A1 (EP)
Inventor: PARK JOON YOUNG
IPC: H04N19/61
Filed: 2012-03-21
Abstract: A video decoding method performed by a decoding apparatus comprises the steps of obtaining video information including a motion vector predictor index, a reference picture index, information on a motion vector difference, and residual information, deriving a first motion vector predictor candidate of a current block from a first neighboring block group based on a first check order, deriving a second motion vector predictor candidate of the current block from a second neighboring block group based on a second check order, selecting a motion vector predictor of the current block among the first motion vector predictor candidate and the second motion vector predictor candidate based on the motion vector predictor index, deriving the motion vector difference of the current block based on the information on the motion vector difference, deriving a motion vector of the current block based on the motion vector predictor and the motion vector difference, generating a predicted block of the current block based on the motion vector of the current block and the reference picture index, generating a residual block of the current block based on the residual information, and generating a reconstructed picture based on the predicted block and the residual block. The first neighboring block group includes a left neighboring block (A<sub>m</sub>) and a bottom left neighboring block (A<sub>m+1</sub>), and the second neighboring block group includes an upper right neighboring block (B<sub>n+1</sub>), an upper neighboring block (B<sub>n</sub>) and an upper left neighboring block (B-1). The first check order is determined in order of the bottom left neighboring block (A<sub>m+1</sub>) and the left neighboring block (A<sub>m</sub>). The first motion vector predictor candidate is derived based on a first condition or a second condition. The second check order is determined in order of the upper right neighboring block (B<sub>n+1</sub>), the upper neighboring block (B<sub>n</sub>), and the upper left neighboring block (B-1). The second motion vector predictor candidate is derived based on the first condition or the second condition. The first condition is whether a block has a reference picture identical to a reference picture of the current block and a reference picture list identical to a reference picture list of the current block. The second condition is whether a block has a reference picture identical to the reference picture of the current block and a reference picture list different from the reference picture list of the current block. For the left neighboring block (A<sub>m</sub>), the bottom left neighboring block (A<sub>m+1</sub>), the upper right neighboring block (B<sub>n+1</sub>), the upper neighboring block (B<sub>n</sub>) and the upper left neighboring block (B-1), the first condition is checked prior to the second condition.When the bottom left neighboring block (A<sub>m+1</sub>) does not satisfy both the first condition and the second condition, it is checked whether the left neighboring block (A<sub>m</sub>) satisfies the first condition or the second condition before checking a third condition that a block has a reference picture different from the reference picture of the current block and a reference picture list identical to the reference picture list of the current block, or a fourth condition that a block has a reference picture different from the reference picture of the current block and a reference picture list different from the reference picture list of the current block for the bottom left neighboring block (A<sub>m+1</sub>). When the bottom left neighboring block (A<sub>m+1</sub>) satisfies the third condition or the fourth condition, a scaled motion vector of the bottom left neighboring block (A<sub>m+1</sub>) is used as the first motion vector predictor candidate, and the scaled motion vector of the bottom left neighboring block (A<sub>m+1</sub>) is derived by scaling based on a distance between a current picture to which the current block belongs and a reference picture of the current block and a distance between the current picture and a reference picture of the bottom left neighboring block (A<sub>m+1</sub>) satisfying the third condition or the fourth condition.